Exploring the efficiency and stability performance of fuel cells without external humidifiers based on real vehicle testing

The fuel cell system without an external humidifier is simpler and more compact, making it suitable for application in the automotive field. Its high output efficiency and stable operating performance are essential conditions for its use in automobiles. In this work, a whole vehicle testing approach was used to study the effects of different output power levels, environmental temperature and humidity on the auxiliary system power consumption, system efficiency, and stability of the fuel cell system without an external humidifier. The results of the study show that the percentage of auxiliary system power consumption is about 10–20 % at 25 °C, and reaches a minimum value of 13.1 % at a slope of about 10 % (stack power is 35.5 kW). The system efficiency reaches a maximum value of 52.6 % at a slope of 4 %. At ambient temperatures of 25 °C with a slope ≥ 14 % and at 40 °C with a slope ≥ 6 %, the outlet coolant temperature of the reactor will exceed 93 °C, which is outside the appropriate temperature range. The difference between the minimum voltage value and the average value of the single cell decreases gradually with decreasing slope. The difference value is maximum at 7.3 mV as the slope is 16 %. Increasing the ambient temperature leads to increase in power consumption of the auxiliary system and decrease in system efficiency. Increasing the ambient humidity results in decreasing the power consumption percentage of the auxiliary system and increasing the system efficiency. Increasing the humidity from 40 % to 80 % decreases the auxiliary system power consumption by 0.81 %. Voltage inconsistency in high temperature and high humidity environments is strongly influenced by the operating conditions.